1. Field of the Invention
This invention relates to a process for preparing a perfluorinated or polyfluorinated aliphatic carboxylic acid that is useful particularly because of their chemical and/or physiological properties.
2. Description of the Prior Art
For the process for preparation of a perfluoroalkyl carboxylic acid from a perfluoroalkyl iodide and carbon dioxide (CO.sub.2), a formerly known method makes use of zinc other metal pair (Japanese Patent Opening Nos. 106808/1977 and 77008/1977). However, this method needs preparation of the metal pair and it is difficult to perform the preparation with good reproducability. Further, the procedure for the reaction is not simple and the yield of the target product is low. A method to make use of an unactivated zinc powder in a similar reaction system has also been disclosed but it is described to yield only a little reaction product of perfluoroalkyl iodide with carbon dioxide gas, the conversion rate, for example, never exceed 7% in case the perfluoroalkyl group contains six carbon atoms. Therefore, also this second method cannot be adapted to be efficient for industrial synthesis.